the 7.62x54mm R is more powerfull than the 30-06, [but not by much], the ammo costs less too if youre not set up for reloading. now if you want something even more powerfull then i suggest an enfield number 4 mark 1 [.303 british] which is is good for anything in north america...
The 303 british is not more powerful than the 30-06.